Kinetic energy = (1/2) (mass) (speed)²
Since the 'speed' in the KE formula is squared, if the car's speed
increases by 5 times, its kinetic energy increases by (5²) = 25 times.
The loss of kinetic energy in a skid is just the wo0rk done by friction
between the tires and pavement. So the skid distance is proportional
to the initial kinetic energy, and the car must skid 25 times as far when
it enters the skid at the higher speed.
25 x 30m = 750 meters
Answer:
When she stretches her arms out,<em> B) her angular speed ω increases due to her moment of inertia decreasing</em>
Explanation:
The angular momentum of a rotating object is defined as the product of its moment of inertia and angular speed.
<em>L = I ω</em>
<em>where</em>
- <em>L is the angular momentum</em>
- <em>I is the moment of inertia</em>
- <em>ω is the angular speed</em>
<em />
According to the principle of conservation of angular momentum, if there is no external torque, angular momentum of the skater must remain conserved. If the initial and final moment of inertia is <em>I_i and I_f </em>while corresponding angular velocities are <em>ω_i and ω_f , </em>then the principle of conservation of angular momentum can be expressed as the following equation:
<em>(I_f) (ω_f) = (I_i) (ω_i)</em>
<em>ω_f / ω_i = I_i / I_f</em>
<em />
From the expression above, we can see that if the moment of inertia decreases, angular velocity would increase to conserve angular momentum of the skater.
Therefore, When she stretches her arms out,<em> her angular speed ω increases due to her moment of inertia decreasing.</em>
The third one is your answer
Answer:
A) Burning fossil fuels pollutes the environment
